1. Field of the Invention
The present invention relates to a label sticking apparatus which can stick labels on mass-produced work-pieces at a high speed, and a label tape suitable for that label sticking apparatus. The present invention relates more particularly to a label sticking apparatus suitable for sticking circular bar code labels on flanges of spools of photographic film cassettes, and a label tape for use in the label sticking apparatus.
2. Related Art
In order to stick labels on work-pieces including articles and parts, various kinds of label sticking apparatus have been known wherein labels are automatically peeled from a label tape by means of a peeling edge, held by pads or drum through vacuum adsorption, and stuck on the work-pieces by means of the pads or the drum.
For example, JPB 63-62422 and U.S. patent application Ser. No. 225,669 (filed on 27 July 1988), now U.S. Pat. No. 4,842,660, disclose a label sticking apparatus which peels labels from a label tape by means of a peeling edge, and adsorptively holds labels on the periphery of a rotary suction drum, and wherein a feed line for feeding work-pieces to be labeled is disposed near the suction drum and driven in synchronism with the rotation of the suction drum so that the labels are successively stuck on the work-pieces which are passed near by the suction drum.
There are also such label sticking apparatus that have a label position adjusting or correcting device. In a known label sticking apparatus as shown in FIG. 11, a label 2a is peeled from a label tape 2 at a peeling edge 3, and attached to a holding-sticking unit 4 by vacuum suction. Thereafter, the orientation or position of the label 2a is corrected by pushing the label 2a with pushing members 5a and 5b in X- and Y-directions individually by an appropriate amount, as is shown in FIG. 12. Then, the holding-sticking unit 4 is moved downward by an up-down cylinder 6, to put the label 2a on a work-piece to be labeled.
In another known label sticking apparatus having a label position correcting device, as shown in FIG. 13, a suction drum 7 is rotated about a vertical axis, and has label holding hooks 7a and bottom supporting bars 7b provided on the periphery thereof. In this apparatus, vacuum adsorbability of a label 2b is lowered before sticking the label 2b, so that the label 2b slips down to the bottom supporting bar 7b due to its weight. As a result, the label 2b is positioned in the vertical direction with its bottom line horizontal. Since the suction drum 7 continues to rotate while the vacuum adsorption is terminated, the label 2b is shifted relative to the suction drum 7 toward the holding hooks 7a. Thus, the label 2b is positioned in the horizontal direction. The label 2b thus correctly positioned is stuck on a work-piece 9 conveyed on a conveyer belt 8.
By the way, it is known in the art to provide DX codes on photographic film or photographic film cassettes so as to facilitate knowing the kind and speed of the photographic film, the number of available frames, the valid period, the production lot number, the manufacturer, and other information by which the photographic film is identified in the factory. The DX codes are, for example, recorded on a magnetic recording layer provided on the photographic film, so as to be read by a magnetic head. Or the DX codes are recorded as bar codes on the outer surface of a cassette shell, to be read by a bar code sensor. Recently, a photographic film cassette having a bar code disc incorporated therein so as to be rotatable along with a spool of the cassette, and a camera having a bar code sensor for reading bar codes on the bar code disc have been disclosed, for example, in U.S. Pat. No. 5,049,912.
Because the bar code disc is made of plastic, it is difficult to print bar codes directly on the bar code disc. For this reason, a label having bar codes printed thereon is stuck on the disc. It is desirable, for sticking the bar code labels on the discs, to use an automatic label sticking apparatus. However, since the bar code disc is circular, the bar code label may also be circular or sectorial, and should be disposed coaxially with the disc. If the rotational axis of the bar code label deviate from that of the disc, the accuracy of decoding of the bar codes is diminished.
The above-described known position correcting devices might be applicable to correct the position of the bar code label. However, the device as shown in FIG. 11 and 12 needs two pushing members for pushing a label in X- and Y-directions, i.e. two-dimensionally, and at least two steps of position correcting operations. Moreover, since the positioning and the sticking are carried out in the same operation cycle using a single holding-sticking unit, it is impossible to achieve a high speed or high efficiency label sticking operation. Not only the device as shown in FIGS. 11 and 12 but also the device as shown in FIG. 13 cannot precisely position circular labels such as the bar code labels, because there is no guide member for determining the center of the circular label. Especially when the angular position as well as the center of the labels are to be exactly determined relative to the work-piece to be labeled, the known sticking devices cannot sufficiently operate.